What is the initial antiplatelet therapy for suspected acute ischemic stroke?

Initial Antiplatelet Therapy for Suspected Acute Ischemic Stroke

Administration of aspirin 160-325 mg within 24 to 48 hours after stroke onset is recommended as the initial antiplatelet therapy for suspected acute ischemic stroke, after intracranial hemorrhage has been ruled out on neuroimaging studies. 1, 2

Evidence-Based Approach to Initial Antiplatelet Therapy

First-Line Therapy

• Aspirin (160-325 mg):
  • Should be administered within 24-48 hours of symptom onset 1
  • For patients who cannot swallow, rectal or nasogastric administration is appropriate 1
  • Initial loading dose of 160-325 mg, followed by maintenance dose 1
  • Reduces risk of early recurrent stroke and improves long-term outcomes 3

Timing Considerations

• For patients treated with IV alteplase (tPA), aspirin administration should generally be delayed until 24 hours after thrombolysis 1
• For patients not receiving thrombolysis, earlier administration (within 24-48 hours) is recommended 2

Special Scenarios

Minor Stroke or High-Risk TIA

• For minor ischemic stroke (NIHSS ≤3) or high-risk TIA (ABCD2 ≥4):
  • Dual antiplatelet therapy (DAPT) with aspirin 81 mg daily and clopidogrel 75 mg daily may be beneficial 1
  • Should be initiated within 12-24 hours of symptom onset
  • Loading doses: aspirin 160-325 mg and clopidogrel 300-600 mg
  • DAPT duration: 21 days, followed by single antiplatelet therapy 1

Alternative Dual Therapy Option

• Aspirin 75-100 mg daily and ticagrelor 90 mg twice daily may be considered for mild-moderate stroke (NIHSS ≤5) or high-risk TIA 1
• Loading doses: aspirin 300-325 mg and ticagrelor 180 mg
• Duration: 30 days, followed by single antiplatelet therapy 1

Important Caveats and Considerations

Contraindications and Precautions

• Aspirin should not be used as a substitute for IV alteplase or mechanical thrombectomy in eligible patients 1
• Antiplatelet agents should not be administered within 24 hours of tPA administration due to increased bleeding risk 2
• For patients with contraindications to aspirin, alternative antiplatelet agents may be reasonable, though limited data exist 1

Monitoring

• Frequent neurological evaluations are essential:
  • Every 15 minutes during first 2 hours
  • Every 30 minutes during next 6 hours
  • Every hour thereafter 2
• Monitor for signs of neurological deterioration, particularly symptomatic intracranial hemorrhage 2

Ineffective or Harmful Approaches

• Glycoprotein IIb/IIIa receptor antagonists:
  • Abciximab is potentially harmful and should not be used 1
  • The efficacy of IV tirofiban and eptifibatide is not well established 1
• Ticagrelor is not recommended over aspirin in the acute treatment of minor stroke 1
• Urgent anticoagulation for non-cardioembolic stroke is not beneficial and increases bleeding risk 2

Long-term Management

After the acute phase, transition to appropriate long-term antiplatelet therapy based on stroke etiology:

• For non-cardioembolic stroke, options include:
  • Aspirin (75-100 mg daily)
  • Clopidogrel (75 mg daily)
  • Aspirin/extended-release dipyridamole (25 mg/200 mg twice daily)
  • Cilostazol (100 mg twice daily) 2

The evidence strongly supports aspirin as the initial antiplatelet therapy for suspected acute ischemic stroke, with specific timing and dosing considerations based on individual patient factors and whether thrombolytic therapy is administered.